Study on Stern Flow and Propeller Performances of a Ship

1)舵作用下的入流速度变化和螺旋桨推力、转矩波动采用旋涡格模型对螺旋桨和舵的影响进行了理论计算，对舵作用下的入流速度变化和螺旋桨叶片推力、转矩波动进行了理论计算。这种波动量不小，在分析螺旋桨非定常特性时应予以考虑。2)用涡点阵法理论计算定子螺旋桨在均匀流动中的推进性能通过在螺旋桨后安装定子叶片，可以减少螺旋桨滑移流中旋转流动的能量损失，从而提高螺旋桨效率。我们称之为定子螺旋桨。模型试验证明了定子螺旋桨的改进。本文提出了一种利用涡点阵法计算定子螺旋桨推进性能的理论方法。本文采用三维边界层理论的积分方法，结合外部势流的朗肯源方法，求解了边界层与船周波的相互作用问题。通过LDV实验和保角映射理论研究了螺旋桨对方向舵的影响以及有和没有螺旋桨时方向舵周围流动的差异。

1) Variation of inflow velocity and fluctuation of thrust and torque of a propeller due to the effect of rudderThe theoretical calculation has been carried out on variation of inflow velocity induced by the rudder and on fluctuation of thrust and torque of a blade of a propeller due to the effect of the rudder by the method employing the vortex lattice model to the propeller and the rudder. The amounts of such fluctuations are not small, so that they should be taken into consideration in analysis of unsteady characteristics of a propeller.2) Theoretical calculation of propulsive performances of stator-propeller in uniform flow by vortex lattice methodBy fitting stator vanes behind a screw propeller, energy loss of rotational flow in the slip stream of the propeller can be reduced and hence the propeller efficiency can be improved. We call it stator-propeller. The improvement of the stator-propeller has been proved by model experiments. In the present research a theoretical method to calculate the propulsive performances of stator-propeller has been developed employing vortex lattice method.3) Interaction problem between boundary layer and waves around a shipThe interaction problem between boundary layer and waves around a ship has been solved by a integral method of three-dimensional boundary layer theory in combination with Rankine sources method for exterior potential flow.4) Mutual interaction between propeller and rudderThe effect of propeller on rudder and the difference of flow around the rudder with or without the propeller have been investigated experimentally using LDV and theoretically by the conformal mapping.